Pubertal development, basal gonadotrophin, and oestradiol levels were assessed in 21 girls who had received neuroaxis irradiation for a brain tumour followed by adjuvant chemotherapy with carmustine (BCNU) or lomustine (CCNU) and procarbazine. Thirteen received chemotherapy before the age of 11 years. Ten remained prepubertal at their last assessment, nine of whom showed biochemical evidence of primary ovarian failure. The remaining three were pubertal or adult, and although basal follicle-stimulating hormone (FSH) and luteinising hormone (LH) levels were normal, all had shown abnormalities of gonadotrophin secretion previously. Eight girls received chemotherapy after 11 years of age. Only three girls exhibited an elevated basal FSH level or exaggerated FSH response to GnRH. Elevated basal FSH values had been noted previously in two of the other five girls. All girls entered or progressed through puberty spontaneously. Seven experienced menarche at an appropriate age. However in four, gonadotrophin levels, which had been elevated, were now within the normal range. In two, menses had continued throughout with normal midfollicular oestradiol levels, whilst the other two developed secondary amenorrhoea associated with radiation-induced gonadotrophin deficiency. The majority of girls showed evidence of primary ovarian dysfunction. This did not prejudice pubertal development or the timing of menarche. Ovarian function may return to normal in the years after treatment, indicating a potential for fertility.